Product hybridization design is a new model of integrated innovation. Existing methods of product hybridization design focus on technological recombination, and there is a lack of research from the perspective of function. Therefore, this paper proposes the concept of functional product hybridization. Obtaining goal products and fusing the existing product function systems are two keys to implementing product functional hybridization. However, existing functional integration methods acquire goal products too widely, and there is less research on fusing product function systems. In this paper, a scenario analysis model based on the divergence tree is established by combining scenario analysis and the divergence tree, and three paths of goal product prediction for functional hybridization are proposed. Based on the idea of biological gene recombination, a product gene model and a method of product gene recombination for functional hybridization are studied. Moreover, integrating the Theory of Inventive Problems Solving (TRIZ), a method of establishing a concept structure is proposed. On this basis, a process model for product functional hybridization design is established. An example of a new tree-planting machine illustrates the application of the proposed model. The proposed method enriches the theory of product hybridization design and achieves the fusion of product function systems to meet the multi-functional needs of users.